The Ohio State University proposes to acquire a Bruker solariX 15 tesla Fourier Transform Ion Cyclotron Resonance mass spectrometer (FTICR MS). This versatile high-end instrument will be placed in the OSU Mass Spectrometry and Proteomics Facility (MS&P) within the Campus Chemical Instrument Center (CCIC), a campus-wide Center that is administratively housed in the OSU Office of Research. The instrument will be operated by staff of the MS and proteomics facility and selected highly trained personnel from mass spectrometry and major user research groups. This instrument's main attractive features are its breadth of application, with a dual MALDI and ESI source coupled to ultrahigh resolution and high mass accuracy. The proposed FTICR MS provides resolution of up to 40,000,000, sub ppm mass accuracy, and sensitivity down to the 100 amol range. Fragmentation by collision-induced dissociation and electron transfer dissociation (ETD), in the external collision cell, and sustained off-resonance irradiation (SORI) and electron transfer dissociation in the ICR cell are possible and provide complementary fragmentation information. CASI (Continuous Accumulation of Selected Ions) is available to enrich very low abundant species by trapping in the collision cell, even from tissue imaging. A major user group that already uses mass spectrometry to solve biomedical problems, but that have faced limitations in their research because they do not have access to a higher performance instrument such as the solariX, has been identified. These include faculty from the College of Medicine (Torrelles, Rovin, Freitas, Parthun), the Comprehensive Cancer Center (Clinton), Chemistry and Biochemistry (Bruschweiler, Foster, Musier-Forsyth, and Turro), and Physics (Poirier and Zhong). The types of problems that will be solved for these investigators, and techniques that they will use with the proposed solariX FTICR MS, include (1) high resolution MALDI and MALDI imaging of tissue, (2) detailed high end, top down structural studies of specific histone proteins and post-translationally-modified proteins, (3) native mass spectrometry measurements to gain stoichiometry and topology of protein complexes, and (4) complex mixture analysis for structural characterization of metabolites and metal-DNA complexes. The CCIC MS&P Facility is an established, well utilized university-wide core. It provides an optimum environment for a high end instrument - a vigorous research community with great need for such an instrument and OSU faculty and staff with the enthusiasm and expertise to use the solariX to its greatest potential. If funded, the solariX will be invaluable to a very broad constituency of researchers.